I have a cupcake order for this weekend, gender neutral colors.  I figure yellow and green, but don't know WHICH yellow and green to use to get the really soft looking baby colors.  Any suggestions?  I have pretty much all the Americolors.

Ask the customer.  Let them choose from the colour charts.

I use both Wilton and Americolor.  The final shade depends on the icing recipe and the amount you add.

For pastel shades, you can stick to lemon yellow and leaf green, and add SLOWLY using tip of a fresh toothpick every time you go into the gel bottle.

Hmm .. ok I'll try those colors .. the person throwing the shower isn't picky at all about the colors so she'd tell me to use whatever .. I just needed an idea of what greens and yellows to start with .. thanks!
 

for gender neutral, i'm a big fan of doing an egg shell white and a warm taupe with pearl accents. When my boys were babies, and even when i knew that they were boys, i always went towards a natural color palette instead of  the baby pastels. Maybe that's an option for you? 

I think those colors would be perfect .. I like the more natural colors myself, the only thing is the shower is being done (tablecloths, napkins, etc,) in the baby green's and yellows ..
 

The avocado green is a good color to start with.